/* (non-Javadoc)
* @see org.dyn4j.geometry.Convex#getFarthestPoint(org.dyn4j.geometry.Vector, org.dyn4j.geometry.Transform)
*/
@Override
public Vector2 getFarthestPoint(Vector2 n, Transform transform) {
// transform the normal into local space
Vector2 localn = transform.getInverseTransformedR(n);
Vector2 point = new Vector2();
// set the farthest point to the first one
point.set(this.vertices[0]);
// prime the projection amount
double max = localn.dot(this.vertices[0]);
// loop through the rest of the vertices to find a further point along the axis
int size = this.vertices.length;
for (int i = 1; i < size; i++) {
// get the current vertex
Vector2 v = this.vertices[i];
// project the vertex onto the axis
double projection = localn.dot(v);
// check to see if the projection is greater than the last
if (projection > max) {
// otherwise this point is the farthest so far so clear the array and add it
point.set(v);
// set the new maximum
max = projection;
}
}
// transform the point into world space
transform.transform(point);
return point;
}
/* (non-Javadoc)
* @see org.dyn4j.geometry.Convex#getFarthestFeature(org.dyn4j.geometry.Vector, org.dyn4j.geometry.Transform)
*/
@Override
public Edge getFarthestFeature(Vector2 n, Transform transform) {
// transform the normal into local space
Vector2 localn = transform.getInverseTransformedR(n);
Vector2 maximum = new Vector2();
double max = -Double.MAX_VALUE;
int index = 0;
// find the vertex on the polygon that is further along on the penetration axis
int count = this.vertices.length;
for (int i = 0; i < count; i++) {
// get the current vertex
Vector2 v = this.vertices[i];
// get the scalar projection of v onto axis
double projection = localn.dot(v);
// keep the maximum projection point
if (projection > max) {
// set the max point
maximum.set(v);
// set the new maximum
max = projection;
// save the index
index = i;
}
}
// once we have the point of maximum
// see which edge is most perpendicular
int l = index + 1 == count ? 0 : index + 1;
int r = index - 1 < 0 ? count - 1 : index - 1;
Vector2 leftN = this.normals[index == 0 ? count - 1 : index - 1];
Vector2 rightN = this.normals[index];
// create the maximum point for the feature (transform the maximum into world space)
transform.transform(maximum);
Vertex vm = new Vertex(maximum, index);
// is the left or right edge more perpendicular?
if (leftN.dot(localn) < rightN.dot(localn)) {
Vector2 left = transform.getTransformed(this.vertices[l]);
Vertex vl = new Vertex(left, l);
// make sure the edge is the right winding
return new Edge(vm, vl, vm, maximum.to(left), index + 1);
} else {
Vector2 right = transform.getTransformed(this.vertices[r]);
Vertex vr = new Vertex(right, r);
// make sure the edge is the right winding
return new Edge(vr, vm, vm, right.to(maximum), index);
}
}
